The present invention is directed to a compliance mechanism that is used to maintain a fluid applicator in contact with the surface of an object to which a fluid is being applied. More particularly, the compliance mechanism is constructed so that the fluid applicator will remain in contact with the surface of the object during relative movement between the object and the fluid applicator. In addition, the compliance mechanism allows the fluid applicator to accommodate changes in the shape of the object without losing contact with the object during the fluid application process.
One of the primary applications of the compliance mechanism is the automotive glass industry where the fluid applicator is used to apply various fluids to the edge of the windshield, lights, and back window. The compliance mechanism will be generally described with regard to this particular automotive application. However, it should be understood that this invention is also suitable for a wide range of other fluid applications. The automotive glass application is only one use and is not meant to limit the scope of the applications for the invention.
The invention is particularly adapted for the production of glazing units or window assemblies for automotive vehicles, although it will find utility generally in a great many other fields. Installation of fixed window units in earlier automotive vehicles generally involved manual installation of the glazing unit using suitable mechanical fasteners such as metal clips for securing the unit in the vehicle body, applying sealant around the marginal edges of the glazing unit, and positioning decorative trip strips around the unit to cover the junction between the marginal edges of the glazing unit and the adjacent portions of the vehicle body. Assembly and installation of such units was relatively slow and costly inasmuch as a considerable amount of labor was required. The procedure was not readily adaptable to being speeded up to accommodate increased automobile production line rates, nor was it adapted to being automated.
Efforts to overcome these disadvantages resulted in numerous improved window structures. Thus, unitary window assemblies were developed wherein a sheet of glass was provided with an adjacent peripheral frame, with a gasket of molded material extending between the frame and the peripheral margin of the window to hold the glass sheet within the frame. Fasteners provided at spaced locations along the frame permitted the entire assembly to be guided into position over an appropriate opening in a vehicle and secured to the vehicle as a unit. Such unitary window units reduce the time required and simplify installation in the vehicle opening. However, due to the labor required in manually assembling the frame and gasket on the sheet of glass, the structures are relatively costly.
More recently, in order to eliminate the manual assembly, so-called encapsulated grazing units have been developed wherein individual sheets of glass or laminated glass units are formed with integral frame or gasket members molded and cured in situ by a reaction injection molding (RIM) process. One such process and resulting product is shown and described in U.S. Pat. No. 4,561,625 to Weaver. Such encapsulating glazing units can be fabricated with a minimum of hand labor, and the resulting units can be readily attached to the portions of the vehicle body defining the window openings during assembly of the vehicle.
As described in the aforementioned patent, such encapsulated units are fabricated by disposing a predetermined portion of the marginal periphery of a sheet of transparent material within a mold structure. A polymeric gasket forming material is injected into the mold cavity and cured in situ on the sheet to encapsulate the marginal peripheral edge portion of the sheet. The resulting assembly can then be readily attached to the body portion defining the periphery of a window opening during manufacture and assembly of a vehicle.
Due to the nature of the glass surfaces, it is known that the gasket materials may not form a permanent, long term bond directly to the glass. Thus, they may not maintain adhesion to the glass surface for a length of time consistent with the life of the automobile. Exposure to weather moisture and sunlight, as well as other factors, may cause the gasket material to loosen from the glass with the passage of time, and ultimately to separate entirely from the glass. In order to improve the adherence of the gasket material to the glass and increase the service life of the encapsulated units to an acceptable level, it has been common practice to apply a coating of a liquid primer material to the affected surface of the glass prior to formation of the gasket thereon. Heretofore, this has been accomplished as by manually painting a band of the primer material along the appropriate edge portion of the glass panel. Such a procedure may, for example, utilize a brush periodically dipped in a container of the primer material, or a plastic squeeze bottle containing the primer material and having a suitable dispensing tip. In any event, the procedures are not entirely satisfactory in that they are time-consuming, labor-intensive and may not result in a satisfactory coating of the primer material. Thus the primer layer, which is generally a urethane material, should be applied as a uniform, continuous, relatively thin band in order to function properly. Should the layer be of excessive thickness, it may separate within the layer along a cleavage plane, resulting in failure of the bond. Of course, if the layer is not of sufficient thickness or if certain areas are not coated, the primer layer would likewise be ineffective for its intended purpose. The primer, and particularly the solvent therefore, may be toxic in nature so that manual application thereof, particularly when using an open container of the primer, may require use of protective equipment by the workers. Such manual application processes also generally result in waste of the primer material and generally messy conditions in the work place. Due to the difficulty in controlling the width of manually applied bands, it may also be necessary to mask the work piece prior to application of the primer material.
The term xe2x80x9ccompliancexe2x80x9d has been applied to the interface between a tool and the product that the tool is designed to act upon. A programmed robot or other motion device can be used to define a travel path that coincides with the perimeter or across a product. One primary application involves the deposition of primers, paint, and activators, adhesives, etc. to aid in the attachment of foam tapes, plastic moldings, metal components such as hinges, locks and all types of encapsulated products. In the process of applying a liquid primer to a defined surface it is desirable to have resiliency between the primer depositing pad or brush and the coated product. The soft touch and feather-like contact (resembling the fine touch of an artist) is the ideal result to give the designed coverage, exact line demarcation and long applicator life. The invention has the capability of being mounted on the robot arm, the arm of a work station module or on a stationary gantry type device that moves the product to be coated to give the desired coverage. The compliance unit of this design, provides the tracking resilience that is required in many robotic applications. Such tracking is virtually impossible to achieve with a robot because of the variable curvatures of the products and the almost impossibility of programming a robot to exacting dimensions on a non-uniform product.
Attempts have been made to automate the application of the primer material to the edge of a glass surface. U.S. Pat. No. 5,131,349 shows one method for automating the application of the primer material. However, the glass surfaces, especially in automotive applications, frequently change in contour and shape, and it is difficult to maintain the fluid applicator described in the ""349 patent in contact with the glass surfaces. It is also difficult to maintain a very light contact pressure between the fluid applicator and the glass surfaces so that a desired thickness of primer is uniformly applied.
Thus, there is a need in the industry for a compliance mechanism that can maintain contact with a surface that changes in contour and shape. There is also a need for a compliance mechanism that maintains a light contact pressure with the surface of the object that is to be primed or coated. There is also a need in the industry for a compliance mechanism that can apply a primer or coating at a desired thickness in a uniform manner.
This invention consists of a compliance device that is used to apply a liquid to a product, primarily glass, in a precision lay down pattern, utilizing specialized and unique flow applicator tips. Some of the 20 applicator tip designs have been documented in U.S. Pat. No. 5,131,349.
In the process to apply primers, adhesives, promoters, etc. to automotive glass and like application, it is necessary to maneuver the specialized tip applicators into many angular modes to provide constant regulated pressure contract with the glass. It is also necessary to maintain band width coverage on all designated surfaces and at the same time control the mill thickness of the fluid that is applied to meet the required quality standards.
There are many applications where the design of the product demands a non-uniform and constant changing band width on one or two edges or on one or both sides of the light and/or a mixture of these variables on a single piece of glass. To accomplish such requirements, it is frequently necessary to employ two different applicator tip designs. On one portion of the product, it may be necessary to have a vertical placement of the applicator tip with respect to the product. On another section of the product, it may be necessary to use the applicator tip in a horizontal mode. Many design factors of the product dictate the ability or inability to perform the required liquid lay down in one cycle.
The capability to perform this type of complex pattern for liquid lay down in a rapid, single automatic cycle has been accomplished with the design of the compliance mechanism that can rotate within its mounting to position the fluid dispenser in either a vertical or horizontal position or an angular position between vertical and horizontal.
A compliance mechanism is disclosed for maintaining a fluid applicator in contact with the surface of an object to which a fluid is being applied. The compliance mechanism includes an L-shaped bracket having a first leg and a second leg. A first tab is positioned at the end of the first leg and a second tab positioned at the end of the second leg. A first dual acting fluid operated cylinder is slidably positioned on the first leg of the L-shaped bracket. The first cylinder has a piston rod that extends from the first cylinder and the fluid actuation of the cylinder causes the piston rod to be advanced relative to the first cylinder. The end of the piston rod that extends from the first cylinder is secured to the first tab. A second dual acting fluid operated cylinder is slidably positioned on the second leg of the L-shaped bracket. The second cylinder has a piston rod that extends from the second cylinder and the fluid actuation of the cylinder causes the piston rod to be advanced relative to the second cylinder. The end of the piston rod that extends from the second cylinder is secured to the second tab. A fluid applicator is positioned on the first cylinder for applying a fluid to the object. The first cylinder allows the fluid applicator to move relative to the object in first direction and the second cylinder allowing the fluid applicator to move relative to the object in a second direction whereby the fluid applicator is maintained in contact with the object during the application of the fluid to the object.
It must be pointed out that the compliance mechanism and the associate fluid dispenser and applicator tip can be mounted on the end of a robot arm to apply a fluid by advancing the applicator tip with the robot arm over the stationery glass product. It is also possible to move the glass product relative to the applicator tip during the fluid application process.